S35390A datasheet(13/51 Pages) SII

13 / 51 page

FOR AUTOMOTIVE 105°C OPERATION 2-WIRE REAL-TIME CLOCK

Rev.2.2_00

S-35390A H Series

Seiko Instruments Inc.

2. Status register 1

Status register 1 is a 1-byte register that is used to display and set various modes. The bit configuration is shown below.

RESET

12 / 24

R / W

SC1

BLD

INT2

POC

INT1

SC0

R / W

Read

Write

R / W

: Read / write

Figure 11 Status Register 1

B0: POC

This flag is used to confirm whether the power is on. The power-on detection circuit operates at power-on and B0 is

set to "1". This flag is read-only. Once it is read, it is automatically set to "0". When this flag is "1", be sure to initialize.

Regarding the operation after power-on, refer to " Power-on Detection Circuit and Register Status".

B1: BLD

This flag is set to "1" when the power supply voltage decreases to the level of detection voltage (VDET) or less. Users

can detect a drop in the power supply voltage. Once this flag is set to "1", it is not set to "0" again even if the power

supply increases to the level of detection voltage (VDET) or more. This flag is read-only. When this flag is "1", be sure

to initialize. Regarding the operation of the power supply voltage detection circuit, refer to " Low Power Supply

Voltage Detection Circuit

B2: INT2, B3: INT1

This flag indicates the time set by alarm and when the time has reached it. This flag is set to "1" when the time that

users set by using the alarm interrupt function has come. The INT1 flag at alarm 1 interrupt mode and the INT2 flag

at alarm 2 interrupt mode are set to "1". Set "0" in INT1AE (B5 in the status register 2) or in INT2AE (B1 in the status

register 2) after reading "1" in the INT1 flag or in the INT2 flag. This flag is read-only. Once this flag is read, it is set to

"0" automatically.

B4: SC1, B5: SC0

These flags are SRAM type registers, they are 2 bits as a whole, can be freely set by users.

B6:

This flag is used to set 12-hour or 24-hour mode. Set the flag ahead of write operation of the real-time data register in

case of 24-hour mode.

0: 12-hour mode

1: 24-hour mode

B7: RESET

The internal IC is initialized by setting this bit to "1". This bit is write-only. It is always "0" when reading. When

applying the power supply voltage to the IC, be sure to write "1" to this bit to initialize the circuit. Regarding each

status of registers after initialization, refer to " Register Status After Initialization".

S35390A Datasheet(PDF) 13 Page - Seiko Instruments Inc

S35390A Datasheet(HTML) 13 Page - Seiko Instruments Inc

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